1. Field of the Invention
This invention relates to a hand tool for use with orthodontic brackets that are directly secured to the enamel surfaces of teeth by an adhesive. More particularly, the present invention relates to a hand instrument for detaching orthodontic brackets from teeth as well as methods for detaching orthodontic brackets from teeth.
2. Description of the Related Art
Orthodontic treatment is directed to movement of malpositioned teeth to improved positions in the oral cavity. Orthodontic treatment can greatly enhance the patient's facial appearance, especially in areas near the front of the patient's mouth. Orthodontic treatment can also improve the patient's occlusion so that the teeth function better with each other during mastication.
One type of orthodontic treatment involves the use of a set of appliances and archwires that are commonly known collectively as “braces”. During treatment, tiny slotted appliances known as brackets are affixed to the patient's anterior, cuspid and bicuspid teeth, and an archwire is placed in the slot of each bracket. The archwire forms a track to guide movement of the teeth to orthodontically correct positions. Ends of the archwire are often received in the passages of small appliances known as buccal tubes that are affixed to the patient's molar teeth.
In the past, orthodontic brackets were commonly welded or brazed to bands that were placed around the teeth. Today, orthodontic brackets are often bonded directly to the enamel surface of the teeth by an adhesive. Once treatment has been completed, the archwire is removed from the slots of the brackets and each bracket is then removed from the associated tooth.
Orthodontic brackets are typically made of metal, ceramic or plastic. Improved ceramic brackets are described in U.S. Pat. Nos. 5,439,379 and 5,366,372. The ceramic brackets described in those patents have two sections that are spaced apart from each other by a channel. In some of the embodiments described in these patents, the bracket sections are connected to each other by a thin web of material that lies along the bottom of the channel and is next to a layer of adhesive that bonds the bracket to the tooth.
The brackets that are described in U.S. Pat. Nos. 5,439,379 and 5,366,372 are debonded from the surface of the teeth at the conclusion of treatment by urging the sections in directions toward each other. Hand instruments that are especially useful for debonding such brackets are described in those patents as well as in U.S. Pat. No. 6,474,988. These hand instruments include wall portions for engaging the sides of the bracket so that the sections of the bracket pivot toward each other and away from the tooth surface when handles of the hand instrument are squeezed together.
There is a continuing need in the art to ensure that all brackets, whether made of ceramic, plastic or metallic materials, are easily debonded from the teeth in a consistent manner at the conclusion of treatment. If, for example, the brackets are constructed to debond from the teeth when sections of the bracket are pivoted together, it is preferable that the sections consistently release from the enamel surface of the teeth in a predictable manner and without undue force. Oftentimes, the patient's teeth are sensitive at the conclusion of orthodontic treatment and for this reason it is desirable to avoid undue pressure or force on the teeth if at all possible.